Suqing Li

Synthesis and characterization of aliphatic segmented poly(ether amide urethane)s through a non-isocyanate route

Two nylon-6 oligomers with polymerization degrees (DP or n) of 6.82 and 4.52 terminated with H2N- and HO-groups (H2N–PAn–OHs) were prepared from caprolactam with ethanolamine via ring-opening polymerization at different molar ratios, and transformed into HO-terminated nylon-6 oligomers (HO–PAn–OHs) through reaction with excess caprolactone. Melt polycondensation of the HO–PAn–OHs, with 1,6-bis(hydroxyethyloxy carbonyl amino)hexane (BHCH) and polyethylene glycols (PEGs), was performed at 170 °C under normal pressure and at 180 °C under reduced pressure of 3 mmHg at different periods. A series of novel aliphatic thermoplastic poly(ether amide urethane)s with different short nylon-6 and PEG segments (s-PEAUs) was prepared. The obtained s-PEAUs were characterized by gel permeation chromatography, FTIR, 1H-NMR, 2D 1H–1H COSY NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The s-PEAUs exhibited an Mn up to 18 400, an Mw up to 48 900, Tm between 145.94 °C and 177.86 °C, initial decomposition temperature of over 253.39 °C, and tensile strength up to 30.03 MPa with elongation at break of 286.8%. Some urea linkages were formed during transurethane polycondensation.

Crystallizable and tough aliphatic thermoplastic poly(ether urethane)s synthesized through a non-isocyanate route

A simple non-isocyanate route synthesizing aliphatic thermoplastic poly(ether urethane)s (PEUs) with good thermal and mechanical properties is described. Melt transurethane polycondensation of 1,6-bis(hydroxyethyloxy carbonyl amino)hexane (BHCH) with two ethylene glycol oligomers, i.e. triethylene glycol (3EG) and tetraethylene glycol(4EG), was conducted, and high molecular weight PEUs were prepared. The PEUs were characterized by gel permeation chromatography, FT-IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray scattering, and tensile tests. The PEUs exhibited Mn above 32000, Mw above 54300, Tg ranging from 11.2 °C to 28.2 °C, Tm from 103.7 °C to 150.6 °C, and initial decomposition temperature over 237.4 °C. A PEU prepared at a BHCH/4EG molar ratio of 5:1 exhibited the best mechanical properties with tensile strength of 32.82 MPa and strain at break of 151.82%. Some urea linkages were formed due to a back-biting side reaction in the transurethane polycondensation.

Aliphatic thermoplastic polyurethane-ureas and polyureas synthesized through a non-isocyanate route

A simple non-isocyanate route for synthesizing aliphatic thermoplastic polyurethane-ureas (TPUUs) and thermoplastic polyureas (TPUreas) is presented. Melt transurethane polycondensation of isophorone diamine or diethylene glycol bis(3-aminopropyl) ether with bis(hydroxyethyl) hexanediurethane, bis(hydroxyethyl) isophoronediurethane or bis(hydroxyethyl) piperazinediurethane was conducted at 170 °C under a reduced pressure of 3 mmHg. A series of thermoplastic TPUUs and TPUreas were prepared, and were characterized by gel permeation chromatography, FT-IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, and tensile testing. The TPUUs and TPUreas have an Mn up to 14 900 g mol−1, an Mw up to 43 700 g mol−1, Tg between −18.6 °C and 116.8 °C, and an initial decomposition temperature of over 222.3 °C. A flexible TPUU exhibits a melting temperature of 77.7 °C, a tensile strength of 6.46 MPa, and an elongation at break of 180.20%.

Aliphatic thermoplastic poly(ether urethane)s having long PEG sequences synthesized through a non-isocyanate route

A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis(hydroxyethyloxy carbonyl amino)hexane with four poly(ethylene glycol)s (PEGs), i.e. PEG400, PEG600, PEG1000, or PEG1500, was conducted at different molar ratios. A series of thermoplastic poly(ether urethane)s (TPEUs) with long PEG sequences were prepared. The TPEUs were characterized via gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The TPEUs exhibit Tg between 12.4 °C and −40.4 °C, Tm of up to 149.8 °C, and initial decomposition temperature over 239.4 °C. The tensile strength of the TPEUs reaches 38.39 MPa with a strain at break of 852.92%.

Synthesis and characterization of crystallizable aliphatic thermoplastic poly(ester urethane) elastomers through a non-isocyanate route

A simple non-isocyanate route is developed for synthesizing crystallizable aliphatic thermoplastic poly(ester urethane) elastomers (TPEURs) with good thermal and mechanical properties. Three prepolymers of 1,6-bis(hydroxyethyloxycarbonylamino) hexane (BHCH), i.e. PrePBHCHs, were prepared through the self-transurethane polycondensation of BHCH. A poly(butylene adipate) prepolymer (PrePBA) with terminal HO― groups was prepared and used as a polyester glycol. A series of TPEURs were prepared by the co-polycondensation of the PrePBHCHs with PrePBA at 170 °C under a reduced pressure of 399 Pa. The TPEURs were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. The TPEURs exhibited Mn up to 23300 g/mol, Mw up to 51100 g/mol, Tg ranging from −33.8 °C to −3.1 °C, Tm from 94.3 °C to 111.9 °C, initial decomposition temperature over 274.7 °C, tensile strength up to 18.8 MPa with a strain at break of 450.0%, and resilience up to 77.5%. TPU elastomers with good crystallization and mechanical properties were obtained through a non-isocyanate route.

Synthesis and Properties of Non-isocyanate Crystallizable Aliphatic Thermoplastic Polyurethanes

A simple non-isocyanate route synthesizing thermoplastic polyurethanes (TPUs) with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.

Amorphous and Crystallizable Thermoplastic Polyureas Synthesized through a One-pot Non-isocyanate Route

A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine, m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas (NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.